Cam grinding fixture



g- 1932- I L. c. SHIPI Y ET AL 1,873,224

CAM GRINDING FIXTURE Filed Nov. 19, 1930 7 Sheets-Sheet l Aug. 23, 1932. c. SHIPPY ET AL CAM GRINDING FIXTURE Filed Nov. 19, 1930 '7 Sheets-Sheet 2 Aug. 23, 1932. L. c. SHIPPY ET AL CAM GRINDING FIXTURE Filed Nov. 19, 1930 7 Sheets-Sheet 5 fimg c. SHIPPY ET AL 1,873,224

CAM GRINDING FIXTURE Filed Nov. 19. 1930 7 Sheets-Sheet 4 Aug. 23, 1932. L. c. SHIPPY ET AL CAM GRINDING FIXTURE Filed Nov. 19, 1930 'T Sheets-Sheet -5 1932- L. c. SHIPPY ET AL 1,373,224

CAM GRINDING FIXTURE Filed Nov. 19, 1930 7 Sheets-$heet 6 OZJWIQ" O m O o O 11 715 E 15 E755 Aug. 23, 1932.

L. C. SHIPPY ET AL CAM GRINDING FIXTURE F iled Nov. 19, 1950 7 Sheets-Sheet 7 mounted in the production cam grinding ap- Fig. 4.

the master control cam whether ornct an Section-being a 'section on thej-line 77-oi 75 734i invention to provide means for making a being related to parts visiblefrom the front 30 Patented Aug. 23, 1932 I I j:

" rs PATENT OFFICE-- [j'j LEO .G. Si-IIPPY ANDfJOI-IN Q. HOLMES,YOF'"ANDERSON, INDIANA, -ASSIGNORS 10 ,DELGO- f 'f RElrIY COREQBATION, OF ANDERSO'N;"IN DIANA, CORPORATION 01? DELAWARE CAM GRINDING FIXTURE m Application filed November 19,1930. serialuaaeaeoo.

This invention relates to the manufacture preferred: embodimentof one form of-the of rotary cams-such as,for example, cams presentinvention:isaclearly shown. for operating the periodic circuit make and In the drawings:

H break apparatus employed in the ignition Fig. 1 is atront-side perspective View of F 5 distributors for internal combustion engines; a cam blank supporting fixtureadapted to be 55 Heretofore it has been the practice of manattachedto the bedlof agrinding machine ufacturers of ignition distributor cams to said fixture embodying the present invenproduce these cams by a grinding machine, tion. the movable arbor of which is controlled Fig. 2 is an end view-on an enlarged scale by a master control cam severaltimes larger of a cam selected asan-zexampleto' show-how '60 than the cam produced the master control the fixture is used "in producing a precision cam being made according to dimensionsdemodel cam. Dimensions 'have been applied rived'byempirical formulae based on the dito the cam shown inFig. 2 toiaicilitate the W mensions proscribed 'for' the ignition disexplanation of the use of the cam grinding it tributor cam. The master control cam not fixture. 05 being even anenlarged scale reproduction F ig. 3. is a rearside perspective viewf of the ignition distributor cam, there was the fixture. no way ofdetermining accurately in advance Fig. 4 is a front View thereof. whether or not the. master control cam when Fig. 5 is a sectional View online 55 of 76 paratus would so control the apparatus that 'Fi'g. 6 is a sectional view-on the line =6-" 6 oi thecams produced would have the required Fig. 4C. dimensions. Furthermore, there was no way Figg'? isa fragmentary plan view looking 0 otdetermining in advance of the making'of in the directionof the arr-ow timthe part-in ignition distributor cam would, if made exig. '5.

actly according to proscribed dimensions, Fig. 8 is 'a rear-end viewer-the fixture;

produce the desired results. I Figs. 9 to 27 inclusive are diagrams'illu s- It is therefore an object of the present trating the use ofthe fixturegthese diagrams full size precision model of ignition distribu ofthe fixture as shown in Fig. =4, for exam tor cams according to the exact dimensions ple. V Y prescribed by the cam designing engineer in Referring to Figs: 1 and 3, '30 designates order to determine whether. or notan'ignithe horizontally m-ovable bed of a grinding tion distributor using. the precision model machine and 31 is the rotatable grinding mawill give the desired result. This precision chine *lo'catedabove the bed-8O in suchposimodel is to be used according to an improved tion that work properly located -"upon the method and as a control cam for use with bed-may be moved-with the bed into contact a precision cam grinding machine described with the grinding-wheel. The-workholdi and claimed in our copending application, ing fixture 'comprises a frame idQ-corhprising SerialNo. 495,628, filed November 14,1980. a base 33 to which uprights SQ -areattached A, second precision grinding machine .disby Welding at 35, the uprightsiiabeing joined closed in our copending application referred by welding at-36 toa tube 37into which bearto uses the master controlcam in thenproing bushings 38 are press fitted.-= Thebearduction of cams which will be substantially ings 38' support a shaft l39' carrying-a head duplicates of the precision models, 40. The shaft 39 receives nuts 39a which Further objects and advantages I of the may be tightened against'a Washer 39%- to presentinvention will be apparent from the take up end play at the shaft 39. The head following description, reference being had 40 provides ways or rails 41 for guid in'g the to the accompanying drawings wherein-a dove-tailshapedeXtensiOn 4r2'of a'slide 43.

slide 43. The slide 43 is generally cylindrical in shape and carries axially thereof afixed rod 51 provldmg a bearing for an 111- dex plate 52 which may be clamped to the slide 43 in various positions of angular adjustment relative thereto by the use of twoclamping screws 53 and cooperating nuts 54, shown particularly in Fig. 6. The slide 43 is provided with an annular slot 55 of T- shaped cross section adapted to receive the head of the screw 53, said head being square or provided with flats to prevent turning in the slot 55. The rod 51 provides a bearing for a second index plate which may be connected with the index plate 52 in various positions of angular adjustment by a peg 61 which fits any one of an annular row of holes 62 in the index plate 60 and a single hole 63 provided by the index plate 52. 'The hole 63 will be vertically below the axis of the rod 51in the normal position of the fixture, that is, when certain graduated scale and indices to be described are in' 'zero registration.

The outer end of the rod 51 is threaded to receive a nut 64 by which a cam blank A which fits snugly with the part 5141!. of the rod 51.may be clamped against the index plate 60 and the plate 60 against the index plate 52. As well known to those skilled in the art of ignition'distributors, the cam drives the dis: tributor rotor through a, tongue and notch connection, the tongue being provided by the distributor and the notch by the cam. This tongue andnotch connection provides means for locating the distributor rotor correctly with respect -tothe lobes of the cam. Ac cordingly, the index plate 62 provides a projection or a tongue 65 received by a notch 66 of the cam blank A as shown in Fig. 2. Therefore, before tightening the screw 64 the blank Aniust be properly located with itsfnotch received by the tongue 65 of the lndex plate 60. The index plate 60 shown is provided with a circular row of eight holes 62 thereby adapting the plate 60 for indexing a cam blank to be formed into a cam having either two, four or eight lobes.* If a cam having three, six or twelve lobes is required, it is obvious that another index plate-60 having twelve holes 62 may be substituted.

Referring to Fig. 7, it will be noted that the index plate 52 carries a .scale70 reading 1n degrees on either side of the zero mark 71. The slide 43 carries a zero mark index 72 co operating with the scale 70.

Theslide43 provides aplane finished surface 75 parallel with the plane finished surface 76 of a stop block 77 attached by screws 78 to the slide 40. Between the surfaces 75 and 76 there may be inserted blocks 79 of various thickness. One of these blocks such as the one shown in Fig. 5 is of suchthickness thatwhen placed between the surfaces 75 and 76 the downward movement of. the slide 43 will beso limited that when it can move no further downwardly, the axis of the rod 51 will be in horizontal alignment with the axis of the shaft 39. Other blocks 79 may be substituted for the one shown, said other blocks being dimensioned to suit the particular cam 1 desired to be produced. When the slide 43 has been adjusted into the desired position with respect to thehead 40 it is secured in the desired position of adjustment by tightening screws 80 which cause blocks 81 to bear.

against the dove-tail shaped extension 42 of the slide 43 thereby clamping the slide 43 to the head 40.

V The head 40 maybe oscillated about the axis of the shaft 39 within certain predetermined limits which are determined by two adjustable stop blocks 82 and 83 adapted to be engaged bya'stop pin 88 fixed to the head 40, said blocks being provided with Vernier indices 84 and 85 respectively which cooperate with graduated scales 86 and .87 carried by a cylindrical stop block support 89 fixed to the'frametube37 by welding as indicated at 90. The stop block support 89 is provided with an arcuate annular groove 91 which is T-shaped in cross section and which receives the heads of bolts 92 which pass through the stop block 82 and 83 respectively and which cooperate with wing nuts 93 to secure the blocks 82 and 83 to the support 89. When the zero marks of the blocks 82 and 83 coincide with the zero marks of the scales 86 and 87 respectively, as shown in Fig. 8, the stop pin 88 will be confined between the blocks 82 and 83 so that the head 40 cannot rotate in either direction, in other words, there'is no lost motion between the pin 88 and the stop blocks 82 and 83. When the stop blocks are located as shown in Fig. 8 the head 40 will be 7 located with its symetrical axis vertical, the

axis of the pin 88 being vertically above the axis of the shaft 39. If, at the same time the zero marks 71 on the part 52 coincide to the zero mark 7 2 on the part 43 as shown in Fig. 7, the hole 63 on the index plate 52 will be vertically below the rod 51.

Having described the construction of our T tical height of the table 30, the table is moved 1 so that the blank will be directly under the wheel 31 with the point Z) tangent to the periphery of the wheel. Then the head 40 i is rotated from the position shown in Fig. 16

to that shown in Fig. 17 in order that the surface ab will be ground as the stop 83"is caused to move into engagement with the stop 88.

. This-is the first surface ab.

, Before grinding the second surface at the pin 61 isremoved from hole 62'No. 7, and

the plate 60 is rotated counterclockwise 90 inorder to locate the hole 62 No.1 in alignment with hole 63 of plate 52." Then the peg 61 is inserted in these aligned holes.

the second surface at. The third and fourth surfaces ab shown diagrammatically in Figs.

'19 and 20 areground in a similar manner,

peg 61 being used to tie hole 62 No. f plate to hole 63 'of/plate 52 preparatory to grinding the third surface-ab as shown in Fig; 19, and peg 61 being used to tie hole 62 No. 5 of plate 60 to hole 63 of plate 52 preparatory to grindingthe fourth surface ab as shown in Fig. 20. I

Before adjusting the fixture for performing the last series of operationswhich grind the-four surfaces '60, the stop block 83is returned to normal position with its zero mark of scale 85 coinciding with zero mark of scale 87 of support 89. The nuts 54 are loosened to permit the return of index plate 52 to normal position with the zero mark 71 of'its scale 'coinciding with Zero mark 72 of slide 43. The Vertical slide 43 is loosened I by loosening the screws and the screw 45 is turned upwardly to permit removal of the .5020 inch set block 79 and the substitution of a .2970 inch set block 79. The slide 43 is then moved downwardly to touch the block and is 54 are then loosened and the index plate 52 is then clamped tight to the head 40. The knobs turned relative to the slide 43 clockwise from the zero position until its 34 9' scale mark Y coincides with the zero mark 7 2 of slide 43. Then the nuts 54 are tightened. vReferring I to Fig. 22 which shows the fixture after these adjustments have been made, it will be noted that the axis of rod 51 will be vertically below the axis of shaft 39 by an amount equal to the difference between .600 inch and .297 inch or .303 inch. Adding this amount -:to .120 inch which is the radius of curvature of the surface be will give the sum .423 inch orone-half of .846 inch which is the diameter of the cam blank circle 100. Therefore, it is apparent that the small circle 39 in Fig. 22 represents the point 6 shown in Fig. 2 which is the center of curvature of the surface to. It is apparent from the foregoing calculations that point I) of the surface 51:50 is located on the cam blank circle 100 and continues from the surface ab.

the head is rotated counterclockwise about the axis of shaft 39 which coincides with center point e shown in'Fig. 2 in order to move the stop 83 away fromthe stop 88 and 4 75 the stop 82 into engagement with thestop88 as shownin Fig. 24 and thus grind the first surface 60. Before grinding the second surface 790 the peg 61 is removed from hole 63 of plate 52 and hole 62 N0. 5 of plate 60 and; 30 plate 60 is'rotated counterclockwise 90 as viewed in Fig. 4 inorder to bring-hole 62. No. 7 into alignment withhole 63 of plate 52, and then the peg 61 is insertedin the aligned holes. Then the oscillation of tl1e 85 head 40 isrepeated in order to grind the second surface 66 in the same manner which was described withrespect to Fig. 24.' The third surface 60 is ground in like manner using the peg 61 in hole 62 No. 1 of plate 60390 as shown in Fig. 26; The fourth surface 50 is ground in like manner using'the peg 61 in hole 62 No. 3 as shown in Fig. 27. This series of operations completes the grinding ofcam A according to dimensions shown iii Fig. 2.

The cam A is now ready to be tested for the accuracy of itsdimensions and for per formance when used in an ignition distributor. If found to give satisfactoryperform ance the cam -A is then used as a control cam for use in a precision grinding machine which grinds the master control camfor mak ing production cams as dlsclosed n our copending application referred to; 1;.1-105 While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms m'ight be adopted, all coming within the scope of theclaims which followtllo What is claimed is as follows:

1. A cam grinding fixture comprising, in combination, a frame for supporting the fixture upon the movable table of a grinder, a shaft journalled in said frame and located parallel to the plane of the grinder table, a head carried by the shaftga slide slidably guided by the head at right angles to the axis of the shaft, 'means for securing the slide to, the head in various positions of linear adjust 'ment, an index plate pivotallv carried by the slide, means securing the index plate to the slide in various positions of angular adjustment, a second index plate rotatably sup-.

ported by the first index plate and located coaxially therewith, means for securing the second index plate to the first index plate in various positions of angular adjustment, means for securing a cam blank to the secondindex plate, and adjustable stops for variably limiting rotation of the head.

2. A cam grinding fixture according to claim 1 in which the slide is moved relative to the head by cooperating screw and nut members one of which is attached to the head and the other to the slide.

8. A cam grinding fixture according to claim 1 in which the head supports a rod providing a pivotal support for both index plates and for a tubular cam blank and the rod has a threaded end cooperating with a nut by which the blank and the second index plate are clamped to the slide.

l. A cam grinding fixture according to claim 1 in which the second index plate provides a locating part engageable with a locating part of the cam blank and is provided with a circular row of indexing holes corresponding in number and spacing to the lobes of the cam to be made from the blank, each of said holes being locatable in alignment with a hole provided by the first index plate, and in which a pin is passed into aligned holes in the index plates to secure them together in a certain angular relation.

5. A cam grinding fixture according to 7 ture upon the movable table of a grinder, a

head rotatably supported by the frame, a

slide carried by the head and linearly adjustable thereon in a direction at right angles to the axis of rotation of the head, a rod supported by the slide and extending with its axis parallel to the axis of the head, the rod being located so that its axis may be moved into or out of alignment with the axis of the head by moving the slide, and means for securing a tubular cam blank upon the rod in various positions of angular adjustment relative to the slide.

In testimony whereof we hereto affix our signatures.

LEO C. SHIPPY. JOHN Q. HOLMES. 

